1. Field Of the Invention
Aspects of this invention relate generally to tracking systems and related methodologies, and more particularly to a system and method for tracking lost subjects using GPS triangulation techniques.
2. Description of Related Art
By way of background, children, adults with challenged mental capacity, and pet animals can easily wander off from their intended location either by disorientation, distraction, theft or kidnapping. Parents and guardians are concerned now more than ever with the increase of kidnappings and foul play on the part of children. Foul play can happen anywhere including the home, parks and forests, schools, public shopping malls, etc. Adults or persons with mental impairments such as Alzheimer's or other mentally challenged persons may not have the capacity to understand boundary limits and are at risk of wandering off without proper supervision. Cats and dogs may also be lost or stolen and cannot find their way back to their homes. With increasing concerns regarding theft, kidnapping, foul play or mental impairments, there is a need for a tracking system and alerting mechanism that incorporates a convenient transponder and receiver that is readily available, portable, convenient and easy to use. Such technology may also find beneficial use in military applications and other such contexts where quickly and easily determining the locations of people or equipment is desired.
The following art defines the present state of this field:
U.S. Pat. No. 5,914,675 to Tognazzini discloses a portable emergency locator device which includes a global positioning system (GPS) receiver generating location data and a wireless telephone transceiver for transmitting the location data as digital data to a called station during a two-way voice conversation via a wireless telephone network (cellular, PCS, or satellite). The emergency locator device can be implemented as a conventional wireless telephone having interfaces for receiving the location data from an external GPS receiver and vehicle status data from external vehicle control systems. The data received from the interfaces is stored in an internal memory for transmission to the called station in response to an emergency event trigger
U.S. Pat. No. 6,014,080 to Layson, Jr discloses a tamper resistant body-worn tracking device to be worn by offenders or potential victims for use in a wireless communication system receiving signals from a global positioning system (GPS). The tracking device directly communicates spatial coordinates to multiple remote sites. The tracking device is an enclosed case worn on a limb of a person. The case contains a battery, a signaling device, and a circuit board containing a field programmable gate array, a wireless data modem, a conventional GPS receiver, and a matched filtering GPS receiver.
U.S. Pat. No. 6,339,397 to Baker discloses a portable self-contained tracking unit which includes an enclosure attached to a mounting plate, with a hollow interior cavity housing a GPS receiver, a microprocessor and a transmitter. The GPS receiver will receive tracking data and the microprocessor will process the tracking data into a data packet. The transmitter transmits the data packet to a remote receiving station, for transmission to a central database. Photoelectric cells are mounted on the enclosure to recharge batteries which provide power to the electrical components of the tracking unit. The enclosure is designed with a pair of vertically oriented side panels which are generally orthogonally oriented so that the solar panels mounted on the side panels will maintain a favorable solar incidence angle during a wide range of orientations. The transmitter is a cellular telephone with an antenna mounted within the enclosure but spaced a distance from the metal mounting plate and electrical components approximately one-quarter wavelength of the operating frequency of the transmitter. The enclosure is formed of a radio frequency and optically transparent material, so that the antenna and the solar panels may be housed within the hollow interior cavity of the enclosure. In the method of the invention, tracking data is periodically transmitted via cellular phone to a cellular service provider, thence to a data service bureau which sends the data over the Internet to the database of a central server computer. The central server computer will decode the information and provide an interface and value added products such as maps and reports for customers via a web page on the Internet.
U.S. Pat. No. 6,819,258 to Brown discloses a system for tracking a person from a system subscriber who affixes a location unit to the person to be tracked, wherein the location unit calculates the location of the person at any given time. The system includes a web host connected to a wide area web network, such as the Internet, the web host includes a computer readable medium and is accessible by the subscriber from a remote computer terminal. A computer program resides on the web host for receiving a tracking request from the subscriber and transmitting a tracking call to the location unit carried by the person. The computer program includes instructions embodied in computer readable code for automatically transmitting the tracking call, receiving location data from the location unit in response to the tracking call, and transmitting the location data to the subscriber's terminal where the current location of the person is displayed.
U.S. Patent Application Publication No. US2005/0017900 to Grimm discloses a tracking unit for assisting in the recovery of stolen monies or other property which includes a housing containing a GPS receiver for receiving GPS signals from overhead satellites, a cellular phone transceiver, a microprocessor, and a battery. Following a theft, the microprocessor activates the cellular phone transceiver to dial the telephone number of a central monitoring station. The microprocessor obtains location data from the GPS receiver and transmits the location data, along with identification information, to the central monitoring station. The tracking unit also includes a separate, conventional RF beacon transmitter for allowing authorities to home-in on the tracking unit within a large building or other structure, either after the GPS signals are lost, or after the location of the tracking unit is localized to a specific building or area.
U.S. Patent Application Publication No. US2005/0020274 to Ursini discloses a child locating device that is compact and portable. It has a multitude of stealth, placement, and deployment applications. It can be disguised on a child's wrist, as a bracelet, pendant, watch, ankle bracelet, pocket item, attached to clothing, worn in hair, or in or on a shoe. The device is activated via internet and/or dialing software. The GPS software then tracks from many locations. Locations include home, office, car, or on foot. The system deploys and tracks from a variety of devices, laptop computer, personal computer, or a hand held computer. It combines hardware, GPS software, telephone line, cellular, and internet into a complete child locator.
U.S. Patent Application Publication No. US2006/0170588 to Chang discloses a tracking method for a cell phone with a positioning device and a system thereof. The longitudinal and latitudinal coordinates of a tracked end in a global positioning system (GPS) are sent to a cell phone of a tracking end via a short message service (SMS). After decoding the short message contents, the longitudinal and latitudinal coordinates are displayed in a geographic information system (GIS) installed in the cell phone.
U.S. Patent Application Publication No. US2006/0176216 to Hipskind discloses an apparatus and methods for tracking an object. The apparatus and methods provide for GPS tracking, and can include a communication system that transmits the position of the object to a central database. Software can track the object and provide updates as to the position, speed, course, and other items of interest.
U.S. Patent Application Publication No. US2006/0223518 to Haney discloses a system for exchanging GPS or other position data between wireless devices for purposes of group activities, child location monitoring, work group coordination, dispatching of employees etc. Cell phones and other wireless devices with GPS receivers have loaded therein a Buddy Watch application and a TalkControl application. The Buddy Watch application communicates with the GPS receiver and other wireless devices operated by buddies registered in the users phone as part of buddy groups or individually. GPS position data and historical GPS position data can be exchanged between cell phones of buddies and instant buddies such as tow truck drivers via a buddy watch server. Emergency monitoring services can be set up with notifications to programmable individuals in case an individual does not respond. Positions and tracks can be displayed. TalkControl simplifies and automates the process of joining talk groups for walkie talkie services such as that provided by Nextel.
U.S. Patent Application Publication No. US2007/0099626 to Lawrence et al. discloses a system and method for determining and communicating the precise location of an individual and/or a motor vehicle in real-time. As an example, a tracking system is disclosed that includes a Global Positioning System (GPS) receiver, a cellular phone, and a processing unit. The GPS receiver, cellular phone and processing unit are arranged as a single, compact tracking unit. The processing unit receives precise location information (e.g., latitudinal and longitudinal coordinates) for the tracking unit from the GPS receiver. A cellular phone capable of receiving text messages (e.g., and/or voice messages) can be used to call the cellular phone of the tracking unit, which responds (e.g., to an authenticated call) by transmitting a text message (e.g., or synthesized voice message) including the precise coordinates of the tracking unit. Thus, either with or without the knowledge of the individual carrying the tracking unit or driving the motor vehicle containing the tracking unit, the system is capable of providing the exact location of the individual and/or motor vehicle to another at any point in time.
U.S. Pat. No. 6,788,200, RE40,879, RE41,087, RE41,102, and RE41,122 to Jamel et al. are directed to a locator unit contained within footwear providing a method for GPS position determination and transmission of said location determination data to a central monitoring station which disseminates the data through the use of proprietary software, wireless communications, land based wire systems and the Internet.
The prior art described above teaches various types of tracking devices, each of which providing a GPS receiver built into the tracking device itself. However, the prior art fails to teach a tracking system or method that utilizes triangulation between a GPS-equipped receiver, such as a cell phone or the like, a transponder located with the subject to be tracked, and at least one satellite/tower in order to locate the transponder based on, or relative to, the GPS coordinates of the receiver. Aspects of the present invention fulfill these needs and provide further related advantages as described in the following summary.